The present invention relates to a fluid apparatus which has a bellows, and which is typified by a bellows type pump and an accumulator for reducing pulsations of such a pump.
As a pump for circulating and transporting chemical liquid in various processes such as washing of surfaces of ICs or liquid crystal display devices in a semiconductor producing apparatus, used is a bellows type pump in which no particles are generated as a result of the pumping operation (for example, Japanese Patent Application Laying-Open No. 3-179184). In a pump of this kind, pulsations are produced by reciprocal motion due to extension and contraction of the bellows. In order to reduce the pulsations, therefore, also an accumulator is used (for example, Japanese Patent Application Laying-Open No. 6-17752).
In such a pump having a bellows, or an accumulator, there arises no problem when chemical liquids or pure water are used as transported liquid. However, a problem is produced in the case where abrasive liquid containing slurry such as silica is used as a polishing solution for Chemical Mechanical Polishing (CMP) of a semiconductor wafer, a hard disk which is to be incorporated into a computer, and the like. In the case where liquid containing a material such as slurry which easily sediments is used, namely, there arise problems such as that the sedimenting material collects on the inner bottom of a liquid chamber of a bellows, particularly, in the vicinity of a discharge port or an outflow port of the inner bottom, and then sets.
The invention has been conducted in order to solve the problems. It is an object of the invention to provide a fluid apparatus which has a bellows, which is configured by a pump or an accumulator, and in which, even in the case where transported liquid containing a sedimenting material such as slurry is used, the liquid can be always smoothly discharged without collecting the sedimenting material on the inner bottom of a liquid chamber of the bellows.
The fluid apparatus having a bellows according to the invention is a fluid apparatus configured by a pump in which a bellows that is extendingly and contractingly deformable in an axial direction is placed in a pump body and set vertically to be driven to perform extending and contracting deformation, and form a liquid chamber inside the bellows, a suction port and a discharge port are formed in an inner bottom face of the pump body facing the liquid chamber, liquid is sucked from the suction port into the liquid chamber by extension of the bellows, and the liquid in the liquid chamber is discharged from the discharge port by contraction of the bellows. In the fluid apparatus, a downward inclination toward the discharge port is formed on the inner bottom face of the liquid chamber.
In the thus configured pump, the axis of the bellows in the pump body is set to be vertical, and the inner bottom face of the liquid chamber in the bellows is formed into a shape in which the face is downward inclined as moving toward the discharge port. Therefore, also liquid containing a sedimenting material such as slurry can be always smoothly discharged toward the discharge port along the downward inclined face of the inner bottom face without collecting the sedimenting material on the inner bottom face of the liquid chamber.
The other fluid apparatus having a bellows according to the invention is a fluid apparatus configured by an accumulator in which a bellows that is extendingly and contractingly deformable in an axial direction is placed in an accumulator body with setting an axis vertical to form a liquid chamber inside the bellows and an air chamber outside the bellows, an inflow port and an outflow port are formed in an inner bottom face of the accumulator body facing the liquid chamber, and a liquid pressure in the liquid chamber balances with an air pressure in the air chamber. In the fluid apparatus, a downward inclination toward the outflow port is formed on the inner bottom face of the liquid chamber.
In the thus configured accumulator, in the same manner as the pump described above, the axis of the bellows in the accumulator body is set to be vertical, and the inner bottom face of the liquid chamber in the bellows is formed into a shape in which the face is downward inclined as moving toward the outflow port. Therefore, also liquid containing a sedimenting material such as slurry can be always smoothly discharged toward the outflow port along the downward inclined face of the inner bottom face without collecting the sedimenting material on the inner bottom face of the liquid chamber.